The invention relates to a vehicle occupant restraint system, in particular to a gas bag module for a vehicle occupant restraint system, and more particular to an elongated side gas bag module.
Side gas bags which in the case of a side impact onto a vehicle protect the head of a vehicle occupant from injuries, are in the meantime being incorporated as a standard fitting in motor vehicles. In a known embodiment, such gas bags are arranged along the roof frame of the vehicle and unfold for example in the manner of a curtain between the side window and the head of the vehicle occupant.
It is important that the gas bag is fully protected up to its unfolding, in order to avoid damage. For this purpose, the gas bag is arranged in a housing, which is often produced from plastic by the injection molding process, the side pieces of which also at the same time form a so-called ejection channel which on activation of the gas bag module provides the unfolding direction of the gas bag. In order to reduce the manufacturing costs, it is favorable to produce the housing from two parts, for example a plastic part designated here as a side piece close to the (vehicle) frame and a side piece designated here as close to the (passenger) interior. The gas bag module is fastened to the vehicle here, for example to its roof frame, such that the side piece close to the frame points to the nearest vehicle wall or to the roof frame and the side piece close to the interior is directed to the interior of the vehicle. Such a housing is described for example in EP 0 952 044 A1. Here, the side pieces are fastened to each other at their edges by means of clip connections. To open the housing to release the gas bag, it is therefore necessary for the clip connection to be designed such that the housing opens reliably by the pressure exerted by the gas bag.
The invention proposes a gas bag module with a housing, which makes possible both a reliable opening to release the gas bag and also a simple installation of the gas bag module.
This is achieved in a gas bag module of the above-mentioned type which comprises a gas bag and a housing with two separate side pieces which define an ejection channel for the gas bag. A first side piece is for being located close to the frame and a second side pieces is for being located close to an interior of the vehicle. The side pieces each have upper and lower ends constituting marginal sections. The side piece which is for being located close to the interior is constructed to be so elastic and to have such a shape adapted to a shape of the side piece for being arranged close to the frame that the side piece close to the interior only rests against an outside of side piece close to the frame and such as to embrace the latter in the manner of a clip. Owing to the elasticity of the side piece close to the interior, the latter can be easily bent up in order to place it onto the side piece close to the frame, and is then fixed in the installed state when both side pieces are placed onto each other, by its elastic action. In this way, the installation of the gas bag module is simplified. Owing to its elasticity, the side piece close to the interior, on unfolding of the gas bag, can be pressed by the latter to the side, in order to clear the way. Due to the overlapping which occurs through the embracing of the marginal sections, the housing is fully closed before the activation of the gas bag module and protects the gas bag from contamination and damage. In the module according to the invention, the two half shells which together form the housing, as a whole form a plug connection which produces a better holding together of the housing parts than in the case of pins formed on at intervals, which form the plug connection.
The side piece close to the frame is preferably constructed so as to be inherently stable. Preferably the side piece close to the frame has a base plate, adjoining which are its marginal sections, and the marginal sections of the side piece close to the interior engage in installed state before an activation of the gas bag module on the rear face of the base plate. In this way, it is ensured that the marginal sections of the side piece close to the interior engage behind the side piece close to the frame so far that the two side pieces remain connected with each other.
Preferably, the side pieces have a C-shaped cross-section. In this way, the straight base plates of the side pieces can form an ejection channel for the gas bag, whilst the connection of the two side pieces with each other and a closing of the housing can take place via the bent marginal sections.
In a preferred embodiment of the invention, the side pieces are fixed to each other in the region of the marginal sections only by the clip-like embracing. This serves to simplify the installation of the two side pieces, because no slip connections have to be brought into engagement. The two side pieces enter into a snap fit through the embracing of the side piece close to the frame by the side piece close to the interior, by which fit the two side pieces are connected with each other. A further advantage lies in that to open the housing on emergence of the gas bag, no clip connection has to be decoupled, but rather only the lower marginal sections of the side pieces have to be displaced with respect to each other.
The cross-section of the marginal sections is preferably in the form of a circular arc. It is particularly preferable for the cross-sections of the respective overlapping marginal sections of the side piece close to the frame and of the side piece close to the interior to have concentric circular arcs. In other words, the marginal sections in the form of circular arcs, of the respectively lower and upper ends of the side piece close to the interior and close to the frame, are coordinated with each other such that after installation sections of the respective marginal sections lie directly on each other. Thus the housing is closed and the gas bag is protected from contamination and damage.
According to a preferred embodiment of the invention, the side piece close to the interior has a hinge so that a section of this side piece can be folded outwards to open the housing. This development facilitates the opening of the housing, in order to allow the gas bag to emerge. If the gas bag module is activated, the unfolding gas bag presses onto the lower ends and hence onto the lower marginal sections of the two side pieces, whereupon the side piece close to the interior is pressed outwards and swings open on its hinge toward the interior of the vehicle, in order to give way for the gas bag. The hinge is preferably arranged approximately in the center of the side piece close to the interior.
Preferably the hinge is a film hinge which is achieved by a reduction of the wall thickness of the side piece in this region.
To simplify the installation of the gas bag module, in a preferred embodiment a device is provided via which the side pieces can be fixed to each other during the composing of the side pieces. In a simple manner, such a device can be realized in that on one of the side pieces domes are formed which have recesses into which pins formed on the other side piece engage on installation of the gas bag module and thus can prevent an undesired displacement of the side pieces with respect to each other.
As the snap fit, which is brought about by the embracing of the side piece close to the frame by the side piece close to the interior, generally is not sufficient to hold the housing parts fastened to each other during the unfolding of the gas bag, a further fastening device is necessary. This fastening device is preferably a clamping connection which is preferably arranged outside the overlapping marginal sections.
In a preferred embodiment of the invention, the side piece close to the frame has formed-on domes with recesses and the side piece close to the interior can preferably be fastened to the side piece close to the frame in a simple and favorably-priced manner by plastic nails which can undergo a connection with the recesses.